Alison Wrenne was making waffles for her two young children one morning when abdominal pain forced her to the floor. A neighbor who is a physician assistant urged her to go to the emergency room. Wrong decision, according to her health insurer.

The government must shell out billions of dollars if policymakers want to stabilize health insurance markets created by the Affordable Care Act. That's the message insurers are delivering to a Republican-controlled Congress that is busy dismantling the Obama-era law and may be reluctant to continue propping it up with federal funds.

Exchanges set up by the Affordable Care Act were designed to give customers a chance to shop for coverage and then buy a plan, most with help from tax credits. The idea was that such a marketplace would push insurers to offer affordable plans to compete for customers. But insurers in many markets have been pulling back from the exchanges after losing money.